Transient photovoltage and dielectric relaxation time in porous silicon

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Abstract
Transient photovoltage (PV) measurements have been carried out on free-standing porous silicon of different porosity. For porous silicon of low porosity, fast charge-carrier separation takes place in the surface space-charge region. A retarded component arises in the PV transients due to limitation of the separation of charge carriers by interparticle transport. For nanoporous silicon, the fast component is absent and the PV transients are retarded strongly in time. The maximum of the retarded PV transients is correlated with the dielectric relaxation time which was obtained by using dc conductivity measurements. This opens opportunities to a contactless electrical characterization of porous semiconductors and its application.